diff --git a/IPython/nbformat/v3/nbbase.py b/IPython/nbformat/v3/nbbase.py
index bac60df..032a34f 100644
--- a/IPython/nbformat/v3/nbbase.py
+++ b/IPython/nbformat/v3/nbbase.py
@@ -69,9 +69,9 @@ def new_output(output_type=None, output_text=None, output_png=None,
         if output_text is not None:
             output.text = unicode(output_text)
         if output_png is not None:
-            output.png = bytes(output_png)
+            output.png = unicode(output_png)
         if output_jpeg is not None:
-            output.jpeg = bytes(output_jpeg)
+            output.jpeg = unicode(output_jpeg)
         if output_html is not None:
             output.html = unicode(output_html)
         if output_svg is not None:
diff --git a/IPython/nbformat/v3/nbjson.py b/IPython/nbformat/v3/nbjson.py
index 5c63a4e..be9ee28 100644
--- a/IPython/nbformat/v3/nbjson.py
+++ b/IPython/nbformat/v3/nbjson.py
@@ -46,7 +46,7 @@ class JSONReader(NotebookReader):
         return nb
 
     def to_notebook(self, d, **kwargs):
-        return restore_bytes(rejoin_lines(from_dict(d)))
+        return rejoin_lines(from_dict(d))
 
 
 class JSONWriter(NotebookWriter):